Document FR-A-2 767 096 describes an example of such a track assembly in which each flange of the male track is inserted, at a flange of the female track, between two ball raceways defining a slide path. The track assemblies described in that document are further provided with a U-shaped control bar. Each branch of that U-shape penetrates into the internal space in which it co-operates with a locking mechanism for locking the tracks to prevent them from sliding relative to each other. In order to unlock or to lock the track s so as to prevent them from sliding relative to each other or so as to enable them to slide relative to each other, a user moves the control bar respectively upwards or downwards, via the portion that forms the web of the U-shape.
It can be understand that, in that type of track assembly, which is otherwise entirely satisfactory, the internal space must be sufficient to enable each branch of the control bar to move in a vertical plane to an extent necessary for locking and unlocking the tracks.
In other cases, the internal space must be sufficient to receive the heads of bolts and/or of nuts.
However, developing an internal space that is larger can, in some cases, be achieved to the detriment of the rigidity of the tracks along a horizontal axis perpendicular to the longitudinal axis of the track assemblies.